This invention relates generally to apparatus and method for controllably and accurately dispensing particulate materials. More specifically the invention concerns reliably dispensing particulate materials from a source container to subsequent unit operation process equipment, for example, receiving receptacles on a fill line conveyor for receiving particulates such as toner from a supply hopper through a particulate conveyor to a toner container, or a melt mixing or extruder device. When magnetic particulate materials are selected the invention is accomplished with a high speed filling nozzle assembly in cooperation with an electromagnetic valve assembly. When non magnetic particles are selected the invention is accomplished with a high speed filling nozzle assembly that includes a low surface tension or "non-stick" liner material therewithin. In embodiments a high speed filling nozzle assembly includes a nozzle with gas fluidizing walls, a low surface tension liner material which assists transport of particles through the conduit to the nozzle, and an electromagnetic valve assembly provides exceptionally high fill rates, fill densities, fill accuracies, and clean, non-dribble operation. The nozzle assembly provides for smooth, continuous flow, and high throughput of particulate materials. The electromagnetic valve assembly provides for precise and non-invasive valving for stop-and-start control of the particulate stream, for example, preventing "dribble" or leakage of magnetic particulate materials into a receiving device or vessel. The low surface tension or "non-stick" liner material ensures continuous and non-blocking flow of particulate materials through the filling assembly enabling smooth delivery of material and trouble free operation of the filling apparatus.
The apparatus and method of the present invention solves important filling problems and provides various advantages including: greatly reduced time required to fill particulate receiving vessels in an interruptible yet continuous manner; and reduced leakage and concomitant contamination arising from continuous high speed fill operations.
In the aforementioned copending application U.S. Ser. No. 08/923,016 now U.S. Pat. No. 5,921,295, there is disclosed an apparatus for assisting in filling a container from a hopper containing a supply of powder and includes a low friction compression nozzle.
The apparatus comprises:
a conduit operably connected to the hopper and extending downwardly therefrom, the conduit adapted to permit a flow of powder therewithin; PA1 a nozzle operably connected to the conduit and extending downwardly therefrom, the nozzle defining an inlet thereof for receiving powder from the conduit and defining an outlet thereof for dispensing powder from the nozzle to the container, the inlet defining an inlet cross sectional area perpendicular to the flow of powder and an outlet defining an outlet cross sectional area perpendicular to the flow of powder, the inlet cross sectional area being larger than the outlet cross sectional area; and PA1 a conveyor located at least partially within the conduit, the conveyor assisting to provide the flow of powder from the container, wherein the dimensions of the nozzle are selected so as to provide a ratio of the inlet cross sectional area to the outlet cross sectional area such that the flow of powder does not seize as it progresses through the nozzle. PA1 placing a first container to be filled in filling relationship to a fill tube; PA1 moving a magnetic material from a source thereof through the fill tube to fill the first container with the material; PA1 applying a magnetic force to the material in the fill tube once the first container is filled, the magnetic force being sufficient to hold the material in place in the fill tube; PA1 removing the first container; PA1 placing a second container to be filled in filling relationship to the fill tube; and PA1 removing the magnetic force applied to the material so that the material can move through the fill tube and into the second container. PA1 a conduit operably connected to a source and extending downwardly therefrom, the conduit being adapted to permit a flow of particulate material from the source through the conduit; PA1 a fluidizing nozzle operably connected to the conduit and extending downwardly therefrom, the nozzle defining an inlet for receiving material from the conduit and defining an outlet for dispensing material from the nozzle to a first receiver, the inlet defining an inlet cross sectional area perpendicular to the flow of material and an outlet defining an outlet cross sectional area perpendicular to the flow of material, the inlet cross sectional area being larger than the outlet cross sectional area; the nozzle being adapted with a plenum including an inlet port for receiving compressed gas and a chamber adapted to communicate the gas to porous wall regions of the nozzle, and an outlet port for engaging a vacuum source to continuously evacuate the receiver while the nozzle is engaged with the receiver; PA1 a conveyor located at least partially within the conduit and the nozzle, the conveyor assisting the flow of material from the source to the receiver, and PA1 an electromagnetic valve located adjacent to at least a portion of the conduit, the electromagnetic valve supplying a magnetic force to the material in the conduit and nozzle until a second receiver replaces the first receiver, the magnetic force being sufficient to restrict or stop the material flow through the nozzle. PA1 including the aforementioned apparatus comprising conduit, fluidizing nozzle, conveyor, and electromagnetic valve, and further comprising a second conveyor for conveying a container under the nozzle, the container being vertically spaced from the end of the nozzle; and PA1 an elevator for reversibly elevating and lowering the container so that an opening in the container engages the end of the nozzle and returns the container to the second conveyor when the container is filled with a magnetic material; and PA1 placing a first container to be filled in filling relationship with the nozzle of the aforementioned apparatus including the second conveyor and elevator, and wherein the particulate material is a magnetic material; PA1 driving the particulate material from a source through the conduit with the conveyor to fill the first container with particulate material; PA1 applying a magnetic force to the particulate material in the conduit when the first container is full, the magnetic force being sufficient to hold the material in place in the nozzle and conduit; PA1 removing the first container; and PA1 repeating continuously the sequence of placing, driving, applying magnetic force, and thereafter removing the filled container with an n-th container.
In the aforementioned copending application U.S. Ser. No. 08/540,993 now U.S. Pat. No. 5,839,458, there is disclosed a container filling method for controllably filling a container, and includes:
The aforementioned copending applications are incorporated by reference herein in their entirety.
Toner containers typically have a small opening into which the toner is to be added. Furthermore, the toner containers often have irregular shapes to conform to the allotted space within the copying machine. Therefore it becomes difficult to fill the toner container because of the small tube required to fit into the small toner container opening and secondly for all the toner within the container to completely fill the remote portions of the container before the container is full.
The problems associated with controlling the filling of toner containers are largely attributable to the properties of the toner. Toner is the image-forming material in a developer which when deposited by the field of an electrostatic charge becomes the visible record. There are two different types of developing systems known as one-component and two-component systems. In one-component developing systems, the developer material is toner comprised of particles of magnetic material, usually iron, embedded in a black plastic resin. The iron enables the toner to be magnetically charged. In two-component systems, the developer material is comprised of toner of polymer or resin particles and a colorant, and a carrier of roughly spherical particles or beads usually made of steel. An electrostatic charge between the toner and the carrier bead causes the toner to cling to the carrier in the development process. Control of the flow of these small, abrasive and easily charged particles is very difficult. The one-component and two-component systems utilize toner that is very difficult to flow. This is particularly true of the toner used in two component systems. The toner tends to cake and bridge within the hopper. This limits the flow of toner through the small tubes which are required for addition of the toner through the opening of the toner container. Also, this tendency to cake and bridge may cause air gaps to form in the container resulting in incorrect or partial filling of the container.
Attempts to improve the flow of toner have also included the use of an external vibrating device to loosen the toner within the hopper. These vibrators are energy intensive, costly and not entirely effective and consistent. Furthermore, they tend to cause the toner to cloud causing dirt to contaminate the ambient air and to accumulate around the filling operation.
Also, difficulties have occurred in quickly starting and stopping the flow of toner from the hopper when filling the container with toner in a high speed production filling operation. An electromagnetic toner valve has been developed as described in the aforementioned copending U.S. patent application Ser. No. 08/540,993 and U.S. Pat. No. 5,685,348, the disclosures of which are incorporated herein by reference in their entirety.